The Third Generation Partnership Project 2 (3GPP2) Code Division Multiple Access (CDMA), known as 3GPP2 cdma2000, networks supports concurrent services functionality for packet data and circuit switched voice communication). The original system supports packet data and circuits switched voice communication and is commonly referred to as the cdma2000 1X system. The cdma2000 1X system air interface is standardized in 3GPP2 document C.S0001 through C.S0005 and corresponding Telecommunication Industry Associates (TIA) standard TIA-2000. In addition, new packet data standards, such as cdma2000 High Rate Packet Data (cdma2000 HRPD1X ) have been created. The cdma2000 HRPD air interface is standardized in 3GPP2 document C.S0024-A and C.S0063. To ensure communication continuity for a mobile radio communication device moving between overlaid 1x and packet data networks, it is desired to provide Cross-Paging capabilities that enables a mobile unit to be notified of incoming 1x circuit voice calls when the mobile is operating on the HRPD network, and notifies the mobile of incoming packet data in the HRPD packet data network when the mobile is operating on the 1X network.
A 3GPP2 Radio Access Network (RAN) to support cross paging consists of an Mobile Switching Center (MSC), a 1x BS (Base Station), an HRPD AN (Access Network or Access Node), an HRPD PCF, and a Packet Data Serving Node (PDSN) and is standardized for two different RAN architectures in 3GPP2 A.S0008-A and A.S0009. An interworking system (IWS) function has been introduced in 3GPP2 for an access network (AN) and for a packet control function (PCF), depending on the architecture deployed, to connect a HRPD system with a 1X system. However by definition, the IWS can only connect to one 1X mobile switching center (MSC), so the current standard and contributions are based on the prerequisite that mobile's serving IWS connects to mobile's serving 1X MSC. However, this situation cannot be guaranteed due to mobility and real deployment. For example, in the following two scenarios, a mobile's serving 1X MSC is different to the one that mobile's serving IWS connects to.
In a first problem scenario: during a 1X circuit voice call, a mobile can move across a 1X MSC boundary and a HRPD subnet or packet zone boundary while busy with a circuit voice call, i.e. an active handoff occurs. As a result, the mobile cannot perform a HRPD location update during a 1X call, because the mobile does not know that it has changed HRPD subnet and cannot monitor both 1x and HRPD systems simultaneously while it is active on a call. So, from the perspective of a packet data network it is unaware that the mobile's serving MSC has changed, and subsequently the IWS does not connect to the mobile's new serving 1X MSC.
In a second problem scenario: in the real deployment, a serving HRPD subnet or packet zone may be split into two areas that are served by independent 1X MSCs. For example, a western geographic area can be covered by 1X MSC1, and an eastern geographic area is covered by 1X MSC2. If it is assumed that the IWS connects to MSC1, for a mobile in the east area, its serving IWS does not connect to its serving 1X MSC, i.e., MSC2. As a result, the mismatch in above two problem scenarios will cause cross-paging to fail, since the current 3GPP2 standard and contributions do not solve the above-mentioned issues.
What is needed is a technique to guarantee that HRPD to 1x Cross-Paging always works, no matter how a serving 1X MSC or serving HRPD subnet are changed, or how a HRPD subnet is overlaid in the real deployment.